Mimic positioning controller for a hydraulically actuated back hoe

ABSTRACT

A mimic positioning control system for a hydraulically powered back hoe which utilizes present day devices such as; the main engine driven hydraulic pumps; hydraulic work cylinders for powering the dipper, dipper arm, and crowd arm main digging members, and fluid motor for swinging that entire digging assembly; pilot actuated directional valves for controlling the direction and flow of fluid between the main pump(s) and the work cylinder or motor; and separate pilot signal devices, requiring small movement, for controlling each separate directional valve; the signal devices then being mounted on a unique arrangement of small scale members which are driven by mechanical linkage, to continuously mimic the position of the main digging members and swing assembly; the signal devices then being actuated by the operator through unique small scale pattern members with the pattern control knob representing the pivot joint position of the main dipper to the main dipper arm so that differences in equivalent position of the control knob from the main dipper cause pattern members and signal devices to actuate respective main, and mimic members through positive mechanical feedback, to move to eliminate the position difference.

United States Patent 1 Strickland, Jr.

[ Apr. 29, 1975 1 1 MIMIC POSITIONING CONTROLLER FOR A HYDRAULICALLYACTUATED BACK HOE [76] Inventor: William A. Strickland, Jr., 5

Marberne Ter., Livingston NJ. 07039 [22] Filed: Feb. 11, 1972 [21] Appl.No.: 225,385

[52] U.S. Cl 214/138 R; 214/1 CM [51] Int. Cl B66f 19/00 [58] Field ofSearch. 214/138 R, 1 CM; 74/388 R, 74/491, 469

[56] References Cited UNITED STATES PATENTS 2,536.724 l/l95l Clay 214/1CM 3,212,651 l0/l965 Spccht et 214/] CM 3.214.040 [0/1965 Willinger214/138 R 3.241.687 3/1966 Orloff 214/1 CM 3.698.580 10/1972 Carlson214/138 R FOREIGN PATENTS OR APPLICATIONS 847.656 9/1960 United Kingdom214/] CM Prinmry E.\'aminerRobert J. Spar Assistant E.\'uminerKennethNoland [57} ABSTRACT A mi mic positioning control system for ahydraulically powered back hoe which utilizes present day devices suchas; the main engine driven hydraulic pumps; hydraulic work cylinders forpowering the dipper, dipper arm, and crowd arm main digging members, andfluid motor for swinging that entire digging assembly; pilot actuateddirectional valves for controlling the direction and flow of fluidbetween the main pump(s) and the work cylinder or motor; and separatepilot signal devices, requiring small movement, for controlling eachseparate directional valve; the signal devices then being mounted on aunique arrangement of small scale members which are driven by mechanicallinkage, to continuously mimic the position of the main digging membersand swing assembly; the signal devices then being actuated by theoperator through unique small scale pattern members with the patterncontrol knob representing the pivot joint position of the main dipper tothe main dipper arm so that differences in equivalent position of thecontrol knob from the main dipper cause pattern members and signaldevices to actuate respective main, and mimic members through positivemechanical feedback, to move to eliminate the position difference.

5 Claims, 3 Drawing Figures MIMIC POSITIONING CONTROLLER FOR AHYDRAULICALLY ACTUATED BACK HOE This disclosure is similar to US. Pat.No. 3.144.146 but differs from that patent in that I here describe themeans of applying a mimic positioning controller to a hydraulicallyactuated back hoe instead of an electrically powered shovel or dragline.

DESCRIPTION OF DRAWINGS FIG. 1 is a rear elevational view of the backhoeas mounted on the rear of a tractor. Main digging members dipper. dipperarm. crowd arm and swing assembly are shown together with the mechanicallinkage means of transmitting the the dipper angle and crowd arm angleto the small scale mimic members which are mounted on a structure abovethe swing motor.

FIG. 2 shows the opposite side of the backhoe together with mechanicallinkage means to transmitting the dipper arm angle to the mimic dipperarm.

FIG. 3 is a rear side elevational view of the mimic members. signaldevices. pattern members and control knob together with some of themechanical linkage used to drive the mimic members to the equivalentposition of respective main members.

Please refer to FIG. 1, which is an illustration of a typical. presentday back hoe as might be mounted at the rear end ofa tractor. Thetractor engine is normally used to power hydraulic pumps. Normally fourhydraulic valve reversible controllers are located immediately adjacent.to the right. and to the left. of the operators seat I, (sometimes footpedal controlled valves are located in front of the operators seat forthe swing motion". Thus the four separate lever controller hydraulicvalves would; (a) regulate the flow of oil to hydraulic cylinder 2causing dipper 3 to rotate about axis 4; (b) regulate the flow of oil tohydraulic cylinder 5 causing the rotation of dipper arm 6 about axis 7;(c) regulate the flow of oil to hydraulic cylinder 8 causing rotation ofcrowd arm 9 about axis 10 and; (d) regulate the flow of oil to hydraulicrotary motor 11 causing the entire digging assembly on swing base torotate swing about axis 12.

It takes a good deal of aptitude to coordinate the movements of thedipper. dipper arm. crowd arm. and swing base 13 to remove earth fromthe bottom of a ditch and place it in a pile. parallel to the ditch inan efficient manner. Other jobs assigned to a back hoe such as pickingup a section of drainage tile with a sling and placing the drainage tileaccurately so that it butts against an adjoining tile; requiresconcentrated effort. mature aptitude. and extended practice.

The reason that the control of the hydraulic valve lever requires agreat deal of skill is that the horizontal movement of the levers isarbitrary and in no way bio mechanically associated or similar to theseparate angular movement of each of the back hoe (dipper. dipper arm,crowd arm and base assembly) members.

In order to make the back hoe control job easy. and natural. thisdisclosure outlines a method by which the operator can control themovements of a small, model size. back hoe whose members at all timesrepresent the positions of the main digging members of the machine. Thusthe controlled three dimensional flight path required of the dipperwould be as easy to accomplish by the following disclosed scheme as the3 dimensional path traced by an eating utensil, such as a spoon.

held in a mans hand. A typical hardware arrangement might be as follows:

With reference to FIG. 1. tubular support 14 is mounted on swing base 13and establishes a support point in line with swing axis 12 andimmediately in front of the operators seat. Member 16 is a small scalerepresentation of crowd arm 9 which pivots around axis 17 adjacent tosupport point 12 and always stays parallel to the crowd arm 9 becausethe distance between axes 10 and 19 is the same as the distance betweenaxes 17 and 18 and the connecting rod 82 between axes l8 and 19 is madeto be the same as the distance between axes 17 and 10.

With reference to FIG. 2 the small scale representation 20 of dipper arm6, is arranged to assume the constant, step by step rotary position ofdipper arm 6 about axis 7. Sprocket 21 is affixed to bracket 22 so thatit too rotates with dipper handle 6 about axis 7. Sprocket 21 causesequal sized sprocket 23 to rotate through the same are around axis 19 bymeans of chain 24. Sprocket 23 drives a shaft, with same axis 19. Axes19, 10. 18. 17. 27. 7. and 4 are all parallel. Axis l9 shaft. drivesa'sprocket 25, on the opposite side of crowd arm 9. Sprocket 25 in turndrives the same diameter sprocket 28 through the same are by means ofchain 29. Sprocket 28 fixed to arm 20 then in turn. causes mimic dipperarm 20 to rotate step by step in coordination with the rotation of thedipper arm 6. The ratio of lengths of dipper arm 6 to mimic dipper arm20 is the same as the ratio of crowd arm 9 to mimic crowd arm 16.Thelength of dipper arm 6 is between axes 4 and 7. The length of mimicdipper arm 20 is between axes 27 and 18. The length of crowd arm 9 isbetween axes 10 and 7. The length of mimic crowd arm 16 is between axes17 and 18.

In a similar manner. we will see how mechanical linkage drives sprocket30 as shown in FIG. 3 through step by step representation of the angularmovement of dipper 3 about axis 4. A lever 32 is affixed to dipper 3 andcauses lever 33 on sprocket 37 to move simultaneously through the sameangular position as lever 32 by means of connecting rod 34. Connectingrod 34 is the same length. between axes 35 and 36 as the distancebetween axes 7 and 4. Sprocket 37 causes an equal diameter sprocket 26to rotate the same number of degrees as sprocket 37 by means of chain38. Sprocket 37 is affixed to lever 33. Sprocket 26 rotates about axis19. Sprocket 26 is a double (locked side by side) sprocket which turnsfree with respect to axis 19 shaft and causes an equal diameter sprocket39 to rotate about axis 18 means of chain 31. Sprocket 39 is affixed tosprocket 40. Sprocket 40 (same diameter) causes sprocket 30 to rotatethe same number of degrees around axis 27 by means of chain 41. Valves61 and 62 are affixed to sprocket 30.

We can now see that small mimic member 16 is always at the same angularposition, and thus represents crowd arm 9. Small mimic member 20 isalways in the same angular position and thus represents dipper arm 6.Also. small mi'rn'ic member 30 is always in the same angular positionsand thus represents dipper 3.

With reference'to FIG. 3, the driven. small scale mimic members 16, 20,and 30 will be used to mount the crowd arm. dipper arm. and dipperhydraulic pilot valve assemblies respectively. The crowd arm valves 57and 58 are mounted on mimic crowd arm member 16. Dipper'arm valves 59and 60 are mounted on mimic dipper arm member 20. Dipper valves 61 and62 are mounted on mimic dipper member 30. The main. pilot operated,reversing, spool spring centered. hydraulic valves which supply fluid tomain members 2, 5., 8, and 11, are of present commercial design such asVickers DGl8S4-06 if air pilot actuated; or DG3S4-044D-20 oil pilotactuated; or DG5S4-06 if electric solenoid. pilot actuated.

Signal devices 49, 50, 57, 58, 59, 60., 6I, and 62 are also of presentcommercial design. If the pilot operated, spring centered. main valvesare air pilot actuated, the signal devices could be pilot valves such asAirmatic three way. spring return, plunger operated model 38251 orVickers C-572-E (with plugs inserted to eliminate P open to T whileextended. and P open to 2 while depressed options. thus making it athree way valve. Reference Vickers industrial catalog page fl7. andAirmatic catalog 2000 pg. 6.

Those valve type signal devices have preloaded springs which hold theplungers in the extended positions. Thus, when two pilot valves aremounted on each mimic member 66, 16., 20, and 30, so that each set ofvalves, with plungers fully extended, touch the forward and reversesides of respective pattern members 73, 42, 45, and 48, the patternmembers are said to be forced to a spring centered, neutral position" aslong as the operater is exerting no directional force on control knob71.

As an alternate to the standard commercial equipment line-up indicatedon pages 2, 3. 4, and 5, stepless speed control movement of the maindigging members may be obtained by utilizing alternate Glarban Corp.signal devices and intermediate valves. In this case. where intermediatevalves are to be utilized, the standard commercial reversing hydraulic,pilot operated. .spool spring offset, main valves which supply hydraulicfluid to the main work cylinder 2,5,8 or hydraulic motor 11 may besimilar to Vickers DG3S4062-50.

Intermediate standard commercial control valves for use between signaldevices 49, 50, 57, 58, 59, 60, 61, 62 and the main valves may besimilar to Glarban Corp. model 50(ll electro-hydraulic or Glarban Corp.model 3002, proportional control valves.

The signal devices can be oil or air valves similar to Glarbans series250. In this case, the valve body would be mounted on the mimic memberso that the valve handle stern would be parallel to the pattern member.The pattern member might have two projections that would project atright angles from the pattern member and be, on each side of the valvehandle stem so that when the pattern member moves, the movement would betransferred immediately to the valve handle, and the pattern memberwould be spring centered by the same springs that keep the valve handlespring centered. As an alternate to the stepless Glarban series 250 oilor air signal devices, electro signal devices can be standard,commercial linear potentiometers. with spring extended push rods.

The three leads or tubes to each pair of signal devices as shown in FIG.3 would be, if using an intermediate valve between the signal device andthe main valve, (a) supply source of air, hydraulic fluid. or electricalcurrent (b) return line to the source of power, and (c) and justablepressure or voltage line to the intermediate Glarban valve. Electricsignal devices can use ground return from the intermediate valve bymeans of the controller metal parts. Each pair of standard commercialpotentiometer (valves) are connected with 2.5 volt output in neutral;with 2.5 to 0 volts when one device is actuated or 2.5 to 5 volts if theother potentiometer signal device is actuated.

If step-less speed is required and no intermediate valve is to beutilzed between the signal device and main valvc. then a connectionbetween signal device and the main valve can be made as shown in theGlarban series 700 arrangement.

The above described commercial hardware would allow the positivefeedback, and signal device mounting arrangement with signal controlknob to cause the main members to be moved either by less expensivesingle step speed control or more expensive and elaborate step-lessspeed control. In either case. the signal device or devices used withone motion have two spring extended plungers which are used to keep thepattern member in the spring centered, zero output, control positionwith respect to each associated mimic member as long as the operated isexerting no directional force on the control knob. 1

If the main pilot operated, spring centered, hydrauli valves areelectric solenoid operated, like Vickers DG5S4-06, then the signaldevices could be electrical, commercially available short stroke linearpotentiometers or Microswitches with spring force extended plungers likethe valves mentioned above. Those stepless or step type switches wouldbe positioned on the mimic members in a manner similar to thedescription above and as shown in FIG. three. The Microswitch brandswitches would each have a standard, form C internal contact that would,when forward switch (alone) was actuated, make the circuit to theforward main valve solenoid and break the circuit to the reversesolenoid.

The control leads or tubes entering or leaving each pair of controlsignal devices, as shown in FIG. 3, best represents an air or electricalpilot installation in that only three leads or tubes are shown one forthe power source and the other two for connecting that power source tothe separate forward and reverse sides of the pilot. spool control. endof the main directional valves. Exhaust air can be vented to atmosphere.so no fourth tank return tube is required. With electrical pilotcircuitry, the entire machine and control members are metal, so thatmetal can be the ground return between the power source and the forwardand reverse solenoids. No fourth lead would be required to a pair ofsignal devices.

Ifthe pilot system uses oil, a fourth tube should be used to each pairof signal devices to vent the low pressure side of the main reversingspring centered valve. pilot section to sump.

Immediately adjacent to the small scale, mimic crowd arm 16, (to theright as viewed from above) crowd arm pattern member 42 is mounted so asto pivot around the same axis 17 used by member 16. Crowd arm patternmember 42 has dipper arm pattern member 45 pivoted on it at top point 46and has no connection to sprocket 40 or axis 18. The distance betweenaxes 18 and 17 is the same as the distance between axes 46 and 17.Member 42 is allowed to be displaced slightly from its spring centeredangular position in line with member 16 until it hits pin stops 67 or68.

Angular movement of member 42 with respect to member 16 causes patternmember 42 to actuate either the crowd-in" valve 57 or crowd-out" valve58. If the crowd-in" valve 57 is actuated. air under pressure in supplyline 51 is allowed to flow out of crowd-in hydraulic line 53 to a pilotend of a crowd reversing valve (like Vickers DG 1 884-06 and from thatpilot end exhausted through line 54 and valve 58 to atmosphere. Thus.shaft 72 (as shown in FIG. 1) of hydraulic crowd cylinder 8 would beretracted by oil from main crowd reversing valve causing crowd arm 9 tocrowd-in toward the operator. As crowd arm 9 rotated counter clock wiseabout axis 10 (as viewed in FIG. I) in a crowdin direction. the smallscale mimic crowd handle member 16 would follow step by step. and thusvalve 57 would tend to move away from pattern member 16, stopping thecrowd-in motion. if pattern member 42 were no longer rotated in acounter clock wise direction.

The operators right hand grabs pattern knob 71 as shown in FIG. 3. Theaxis 47 of pattern knob 71 is the same distance from pattern axis 46 asaxis 27 (as shown in FIG. 1) is from axis 18 of the mimic members. Ifthe operators hand signaled a crowd-in motion on knob 71. that signalforce would be transmitted through pattern member 45 to pivot point 46,attached to pattern member 42. Thus pattern member 42 would rotatecounter clock wise until it hits pin stop 67, and in so doing. patternmember 43 would actuate the crowd in valves 57 as previously described.As soon as the operators hand stops the counter clock wise motion.member 45 and 42 would become stationary, but members 9 and 16 wouldcontinue their counter clock wise motion by a small amount untilcrowd-in valve 57 pulls away from the stationary pattern member 42.

The mimic members 16, 20, and 30. on which the respective control valvesare mounted. provide positive feed back of position desired 0 aspatterned by the signal linkage pattern member 42 crowd. 45 dipper arm.and 48 dipper respectively.

The operator by grasping pattern knob 71 and rotating pattern member 45has no connection with sprocket and is tied to knob 71 through a shaftwith axis 47 moves member about pivot 46 in a counter clock-wise motionaway from spring centered alignment with member 20 until the pin stop 69on member 20 restricts further signal motion. When signal member 45moves counter clock-wise with respect to member 20, member 45 actuatesthe dipper arm control valve 60 causing air in line 56 to actuate airpilot. dipper arm reversing hydraulic valves (like Vickers DGI8S406).thus causing shaft 74 of hydraulic cylinder 5 to retract moving dipperarm 6 in a counter clock-wise motion about axis 7; and also moving mimicdipper arm 20 in a counter clock-wise motion about axis 18. As soon asthe operators counter clock-wise movement of pattern knob 71 and patternmember 45 about axis 46 stops. pressure of 45 against control valve 60stops and dipper arm 6 and mimic dipper arm 20 continue to rotateslightly further in a counter clock-wise direction until the dipper armvalves 59 and 60 are equally distant from member 45.

In a similar manner. by rotation of pattern control knob 71 about itsown axis the operator can cause rotation of extension arm 48 affixed toknob 71, and counter clock wise motion of 71 and 48 will actuate pilotvalve 62 allowing the air in supply line 63 to flow out of line 64 tothe pilot end of hydraulic reversing, main (dipper) valve (like VickersDG18S406) and exhaust through line 65 and valve 61 to atmosphere. Oil

from dipper valve thus causing shaft (as shown in FIG. 1) of hydrauliccylinder 2 to retract moving the dipper 3 in a counter clock-wisedirection about axis 4 and simultaneously by means of linkage describedmov ing mimic member 30 in a counter clock-wise direction. When theoperator stops rotation of pattern knob 71 and extension arm 48, valve62 is no longer actuated more than valve 61 and so retraction of shaft75 of hydraulic cylinder 2 stops dipper rotation.

Again. in a similar manner. the operator when sitting on seat 1 cangrasp pattern control knob 71 and apply pressure in a horizontal.counter clock-wise direction about axis 12 (FIG. 1) so that swingpattern plate 44 and plate finger 73 applies more pressure to swingpilot valve 49 than to valve 50 and therefore in a manner similar to theother motions described above. the main swing. air operated. reversingvalve sends oil to the hydraulic rotary actuator so that the hydraulicrotary actuator 79 will swing the entire digging assembly counterclock-wise about axis 12 with respect to stationary seat 1 and plate 66.Valves 49 and 50 are mounted on plate 66. When the operators patternknob 71 plate 44 and finger 73 stop horizontal motion and pressure.pilot valves 49 and 50 will regain equal (spring) force neutral positionand so both digging members and mimic members swing motion also stops.

Tubes 51, 53, and 54 are rigid as shown connected to crowd signaldevices 57 and 58 up to joints 108, 109 and 107 respectively. Tubes 52,55, and 56 are rigid from dipper arm signal devices 55 and 56 to joints104, 106 and respectively. Tubes 63, 64, and 65 are rigid from dipperrotational signal devices 61 and 62 to joints 102, 103 and 101respectively. Tubes 76, 77 and 78 are rigid from swing signal devices 49and 50 to joints 112. 111. and 110 respectively. From the above tubejoints to their respective crowd. dipper arm. dipper and swing mainpilot actuated control valves. the tubes are flexible. Rigid tubesections 51, 52 and 63 could help confine motion of pattern members 42,45 and 48 respectively to movements parallel to their respective mimicmember movements. In any given swing position. pattern members 42, 45and 48 would be in essentially the same vertical plane.

Swing pattern finger 73 actuates swing pilot valve 49 by means of itsspring extended plunger 85, or actuates valve 50 by means of its plunger84. In a similar manner crowd pilot valves 58 or 57 are actuated bycrowd pattern member 42 by means of plunger 94, which is visible in FIG.3 or plunger 95 respectively of valve 57, which is not visible. Dipperarm pattern member 45 actuates dipper arm pilot valve 600 by means ofits plunger 114, or valve 59 by means of its plunger not visible. Alsodipper rotational pattern member 48 actuates valve 62 by means of itsplunger 124, or valve 61 by means of its plunger not visible.

All pairs of valves as mentioned for the swing. Crowd. dipper arm. anddipper movement signal output have spring extended plungers. as related,which force their entrapped related pattern member to a spring centeredneutral position when the operator is exerting no overriding patternforce on control knob 71.

FIG. No. 1 shows the small sized mimic members only on which the pilotvalves are mounted. Pattern members 44, 42, 45 and 48 are omitted fromFIG. No. 1 for clarity.

Vertical support tubes 14 in FIG. 1 become horizontal support tubes 79and 80 as shown in FIG. 3.

Mimic crowd member 16 is strengthened and made more rigid by parallelcrowd mimic member 83.

I claim as my Invention:

1. A controller for a hydraulically driven back hoe; the back hoeutilizing the following present day commercially. available. items:

1. An engine prime mover.

2. Main hydraulic pump or pumps.

3. Hydraulic linear or rotary actuators used to drive the diggingmembers.

4. Main digging members including; (a) a dipper. (b) a dipper arm (c) acrowd arm. (d) rotational (swing) base for members a. b. and c.

5. Hydraulic. pneumatic or electric reversible. stepless signal devices.of standard commercial types. that are used to provide the pilot signalsto hydraulic pneumatic or electric actuated main hydraulic valves thatcontrol the flow of hydraulic fluid to the main actuators that in turncontrol the movement of the dipper. dipper arm. crowd arm. and swingsupport members;

and the following novel assemblies:

A. means for continously transmitting the dippr angle. dipper arm angle.the crowd arm angle. and the swing base position angle-with significientforcegreater than the operators strength to resist that transmittingeffort.

B. a means for representing and mimicing the exact angular position ofthe main digging members (dipper. dipper arm. crowd arm. and rotary orswing base) by small scale equivalent members.

C. means for mounting the signal devices. on the mimic or main membersand which signal devices actuate the means for continuously driving themain and mimic members to follow pattern elements. and

D. pattern control elements that represent the dipper. dipper arm. crowdarm. and swing base. in the same small scale as the mimic members. andlocated with respect to the mimic members so that the pattern membersbreak down the operators hand movement into the proper vector signals ofdirection and speed for each of the four sets of main and mimic membersrequired to make the four main digging and mimic elements actuate thesignal devices and follow the exact relative sequence of positions asset up by the positions of the pattern elements wherein said positionsof the pattern members comprise direction and speed vectors.

2. Controller as described in claim 1 whose sensing devices are mountedon the small scale mimic members. and have spring positioned stems sothat the operator controlled pattern members have to move against thespring centering effort exerted by the four sets of signal devices; theresistive effort of the signal devices against the dipper. dipper armcrowd arm, and swing base pattern members increases as the patternmembers are moved from slightly off neutral in one direction beforehitting mechanical stops; the amount of signal device displacement isproportionate to the force exerted by the dipper in breaking throughearth and rock and thus the operator has an indication of the diggingeffort of the back hoe.

3. A controller for a back hoe as recited in claim 1 where the requiredrelative positions of the dipper to the dipper arm; dipper arm to thecrowd arm; and crowd arm to the swing base are continously coordinatedby the signals from the pattern members to the signal devices on themimic members so that the dipper can follow exactly. step-by-step. thelocus of points set up by the operators hand in small scale.

4. A controller as recited in claim 1 for a back hoe whose main andmimic members follow within an approximate equivalent range of angularpositions signaled by the pattern members: the control knob having adirection and speed vector which is substantially equivalent to the sumof the speed and direction vectors of the pattern members so that thedipper can follow a relative sequence of positions associated with thecontrol knob.

5. A controller whose assembly of control elements as described in claim1 above causes any motion in progress to be self cancelling when thecontrol knob is brought to a stationary position.

1. A controller for a hydraulically driven back hoe; the back hoeutilizing the following present day commercially, available, items: 1.An engine prime mover,
 2. Main hydraulic pump or pumps,
 2. Controller asdescribed in claim 1 whose sensing devices are mounted on the smallscale mimic members, and have spring positioned stems so that theoperator controlled pattern members have to move against the springcentering effort exerted by the four sets of signal devices; theresistive effort of the signal devices against the dipper, dipper armcrowd arm, and swing base pattern members increases as the patternmembers are moved from slightly off neutral in one direction beforehitting mechanical stops; the amount of signal device displacement isproportionate to the force exerted by the dipper in breaking throughearth and rock and thus the operator has an indication of the diggingeffort of the back hoe.
 2. Main hydraulic pump or pumps,
 3. Hydrauliclinear or rotary actuators used to drive the digging members,
 3. Acontroller for a back hoe as recited in claim 1 where the requiredrelative positions of the dipper to the dipper arm; dipper arm to thecrowd arm; and crowd arm to the swing base are continously coordinatedby the signals from the pattern members to the signal devices on themimic members so that the dipper can follow exactly, step-by-step, thelocus of points set up by the operator''s hand in small scale. 3.Hydraulic linear or rotary actuators used to drive the digging members,4. Main digging members including; (a) a dipper, (b) a dipper arm (c) acrowd arm, (d) rotational (swing) base for members a, b, and c,
 4. Acontroller as recited in claim 1 for a back hoe whose main and mimicmembers follow within an approximate equivalent range of angularpositions signaled by the pattern members; the control knob having adirection and speed vector which is substantially equivalent to the sumof the speed and direction vectors of the pattern members so that thedipper can follow a relative sequence of positions associated with thecontrol knob.
 4. Main digging members including; (a) a dipper, (b) adipper arm (c) a crowd arm, (d) rotational (swing) base for members a,b, and c,
 5. Hydraulic, pneumatic or electric reversible, steplesssignal devices, of standard commercial types, that are used to providethe pilot signals to hydraulic pneumatic or electric actuated mainhydraulic valves that control the flow of hydraulic fluid to the mainactuators that in turn control the movement of the dipper, dipper arm,crowd arm, and swing support members; and the following novelassemblies: A. means for continously transmitting the dippr angle,dipper arm angle, the crowd arm angle, and the swing base positionangle-with significient force-greater than the operator''s strength toresist that transmitting effort, B. a means for representing andmimicing the exact angular position of the main diGging members (dipper,dipper arm, crowd arm, and rotary or swing base) by small scaleequivalent members, C. means for mounting the signal devices, on themimic or main members and which signal devices actuate the means forcontinuously driving the main and mimic members to follow patternelements, and D. pattern control elements that represent the dipper,dipper arm, crowd arm, and swing base, in the same small scale as themimic members, and located with respect to the mimic members so that thepattern members break down the operator''s hand movement into the propervector signals of direction and speed for each of the four sets of mainand mimic members required to make the four main digging and mimicelements actuate the signal devices and follow the exact relativesequence of positions as set up by the positions of the pattern elementswherein said positions of the pattern members comprise direction andspeed vectors.
 5. Hydraulic, pneumatic or electric reversible, steplesssignal devices, of standard commercial types, that are used to providethe pilot signals to hydraulic pneumatic or electric actuated mainhydraulic valves that control the flow of hydraulic fluid to the mainactuators that in turn control the movement of the dipper, dipper arm,crowd arm, and swing support members; and the following novelassemblies: A. means for continously transmitting the dippr angle,dipper arm angle, the crowd arm angle, and the swing base positionangle-with significient force-greater than the operator''s strength toresist that transmitting effort, B. a means for representing andmimicing the exact angular position of the main diGging members (dipper,dipper arm, crowd arm, and rotary or swing base) by small scaleequivalent members, C. means for mounting the signal devices, on themimic or main members and which signal devices actuate the means forcontinuously driving the main and mimic members to follow patternelements, and D. pattern control elements that represent the dipper,dipper arm, crowd arm, and swing base, in the same small scale as themimic members, and located with respect to the mimic members so that thepattern members break down the operator''s hand movement into the propervector signals of direction and speed for each of the four sets of mainand mimic members required to make the four main digging and mimicelements actuate the signal devices and follow the exact relativesequence of positions as set up by the positions of the pattern elementswherein said positions of the pattern members comprise direction andspeed vectors.
 5. A controller whose assembly of control elements asdescribed in claim 1 above causes any motion in progress to be selfcancelling when the control knob is brought to a stationary position.